1. Field of the Invention
The present invention relates generally to a semiconductor process, and more specifically, to a semiconductor process that forms at least a recess in a fin-shaped structure beside a gate structure, thereby forming an epitaxial layer having a hexagon-shaped profile structure in the recess.
2. Description of the Prior Art
With increasing miniaturization of semiconductor devices, various Fin-shaped field effect transistor (FinFET) devices have been developed. The Fin-shaped field effect transistor (FinFET) is advantageous for the following reasons. First, manufacturing processes of Fin-shaped field effect transistor (FinFET) devices can be integrated into traditional logic device processes, and thus are more compatible. In addition, since the three-dimensional structure of the FinFET increases the overlapping area between the gate and the substrate, the channel region is controlled more effectively. This therefore reduces drain-induced barrier lowering (DIBL) effect and short channel effect. Moreover, the channel region is longer for the same gate length. Therefore, the current between the source and the drain is increased.
In a current FinFET process, agate structure (which may include a gate dielectric layer, a gate electrode located on the gate dielectric layer, a cap layer located on the gate electrode, and a spacer located beside the gate dielectric layer, the gate electrode and the cap layer) is formed on a substrate having at least a fin-shaped structure. Then, epitaxial layers are formed on the fin-shaped structure beside the gate structure. Thereafter, other processes such as removing spacers of the gate structure may be performed.
However, the epitaxial layers make removal of the spacers difficult. The distance between the epitaxial layers on either side of the gate structure is also too great, resulting in insufficient stress forcing the gate channel below the gate structure, and limited ability to enhance carrier mobility of the gate channel through the epitaxial layers.
Therefore, a semiconductor process, more specifically a FinFET process, which can improve the performance of the epitaxial layers is needed in the industry.